Dental plaque is formed by oral microbes that can selectively adhere to the salivary glycoproteins composing the tooth pellicle. Increased knowledge of the adherence mechanisms will provide a sharper focus for future plaque and disease preventive methodologies, whether they be chemical or immunological. In this proposal, we present data indicating that adherence of Streptococcus metans, a microbe often found in plaque and closely associated with the development of dental caries, is a more complex process which involves at least two reactions. Production of sucrose-derived glucans by S. mutans closely correlates with the microbe's virulence. However, several literature reports indicate that the glucans, by themselves, are insufficient to explain infection by S.mutans. Our preliminary data, on which this proposal is based, indicate that adherence of S. mutans 6715 can be blocked without affecting the glucosyltransferases or the glucan products. We further suggest that initial bacterial attachment to the pellicle is dependent on cell-bound protein while the glucans function as mediators of cell-cell accumulation. In this proposal, we present experimental approaches designed to characterize the attachment of S. mutans to saliva-coated surfaces. Specifically, we plan to: 1) study the growth physiology of S. mutans relative to the attachment reaction; 2) modify chemically both the cell and host attachment receptors; 3) purify the bacterial cell-wall complex and isolate the attachment factor as well as the host receptors; and 4) determine the immunological relationship of the attachment factor to other cell surface proteins and the surfaces of other S. mutans serotypes. In this proposal, we also discuss the value of the Scatchard plot for analysis of adherence data. A plot of our data predicts that there are multiple bacteria binding receptors in the saliva samples used to form the artificial pellicle. Methodologies are presented to determine the basis for the mutliple affinities of the salivary pellicle.